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US 2017/0288548 A1Published application
Negative Current Clocking
AssigneeDialog Semiconductor (UK) Limited
InventorsMark Childs, Paul Collins
Life of this patent
Estimating the term…
Abstract
A switching mode power supply (SMPS) configured for clearing an overvoltage condition. The overvoltage is determined by detecting that the output voltage has exceeded the input voltage by a limited amount. The overvoltage is cleared by repetitively turning on and then off the switches controlling the flow of energy to the SMPS in sequence until the excess charge resulting from the overvoltage is couple to circuit ground, and the output is reduced to within acceptable limits.
Claims28
A switching mode power supply (SMPS) configured for providing a current to a load at an output voltage, comprising:
- a DAC configured for receiving a digitized voltage target signal and configured for generating a target voltage;
- a comparator for comparing the target voltage and the output voltage to determine if the output voltage is less than or greater than or equal to the target voltage and generating a under voltage signal;
- a pulse width modulating (PWM) control circuit configured for receiving the output voltage and the target voltage and configured generating PWM switch control signals for operating the SMPS in a PWM mode for sourcing and sinking current to the load;
- a pulse frequency modulating (PFM) control circuit configured for receiving the under voltage signal and configured generating PFM switch control signals for operating the SMPS in a PFM mode for sourcing current to the load when the load is in low power operation;
- a gate control circuit configured for receiving the PWM switch control signals from the PWM control circuit and PFM switch control signals from the PFM control circuit;
- a first switch having a first terminal connected to receive an input voltage from a power source, a second terminal connected to a first connector of an inductor, and a gating terminal connected to the gate control circuit for receiving a first switch activation signal for connecting or disconnecting the first terminal and the second terminal such that when said output voltage falls below said input voltage, the first activation signal connects the first terminal and the second terminal;
- a second switch having a first terminal connected to the first connector of the inductor, a second terminal connected for sinking excess current to a reference voltage source, and a gating terminal connected to the gate control circuit for receiving a second switch activation signal for connecting or disconnecting the first terminal and the second terminal such that when said output voltage rises above an overvoltage level, the second activation signal connects the first terminal and the second terminal for reducing the overvoltage to within allowable limits by cycling the second switch followed by the first switch a number of times until output voltage of the SMPS is within an upper limit voltage level of the output voltage of the SMPS;
- an active diode block configured for monitoring the current flow through the second switch and for generating a current flow signal indicating that the current flow through the second switch has dropped to zero and connected to the PFM control circuit for transferring the current flow signal to the PFM control circuit, such that the PFM control circuit deactivates the second switch when the current flow drops to zero;
- and
- an overvoltage discharge circuit for eliminating an overvoltage at an output of the SMPS, comprising:
- an overvoltage detection circuit coupled to the output of the SMPS for receiving an indication the output voltage and coupled to the output of the for receiving the target voltage, and configured for determining that the output voltage is greater than the target input voltage and providing an overvoltage indication signal that is a voltage that is not circuit ground;
- a zero crossing comparator circuit coupled to the overvoltage detection circuit for receiving the overvoltage indication signal, coupled to the first connector of the inductor for receiving a voltage level present at the first connector of the inductor, configured for generating a negative current limit/active diode select signal having a first voltage level when the overvoltage indication signal designates an overvoltage condition at the output of the SMPS indicating that a negative the negative current limit indicator/active diode select signal is activated, generating a second voltage level that is approximately ground when the voltage level at the at the first connector of the inductor is approximately equal to the zero voltage level indicating the active diode second switch is activated;
- and
- a switch control circuit coupled to the zero crossing comparator circuit and configured for generating a switch activation/deactivation signal indicating that the second switch is to be activated when the voltage at the first connector of the inductor is greater than the first voltage level;
- wherein when the overvoltage indication signal indicates an overvoltage at the output of the SMPS, the switch control circuit activates the second switch to sink excess current to decrease the overvoltage at the output of the SMPS.
12 more elements
A method for correcting an overvoltage in a switching mode power supply (SMPS), comprising:
- a) detecting an output voltage of a SMPS greater than an overvoltage voltage level;
- b) clocking a first switch to an on state until reaching a negative current limit followed by turning on a second switch and allowing it to discharge extra charge of the SMPS to circuit ground until the output voltage reaches the overvoltage level;
- and
- c) repeating step b) a number of times until the output voltage is reduced to within the under voltage level and the overvoltage level.
1 more element
A method for regulating power in a switching mode power supply (SMPS), comprising:
- a) setting a target voltage;
- b) detecting an output under voltage;
- c) turning on a first switch to charge an inductor with energy;
- d) turning off said first switch upon reaching a current limit;
- e) turning on a second switch upon turning off the first switch, wherein the second switch is controlled as an active diode;
- and
- f) eliminating an overvoltage at an output of SMPS, comprising the steps of:
- detecting an overvoltage by determining that the output voltage of the SMPS is greater than a target input voltage;
- when the output voltage is greater than the target input voltage activating an overvoltage indication signal;
- adjusting the overvoltage indication signal to a voltage that is not circuit ground such that a current at which the second switch turns off is varied;
- generating a negative current limit/active diode select signal having a first voltage level when the overvoltage indication signal designates an overvoltage condition at the output of the SMPS indicating that a negative the negative current limit indicator/active diode select signal is activated;
- generating a second voltage level that is approximately ground when the voltage level at the at the first connector of the inductor is approximately equal to the zero voltage level indicating the negative current limit/active diode select signal is activated;
- generating a switch activation/deactivation signal indicating that the second current limit switch is to be activated when the voltage at the at the first connector of the inductor is greater than the first voltage level;
- and
- when the overvoltage indication signal indicates an overvoltage at the output of the SMPS, activating the second current limit switch to sink excess current to decrease the overvoltage at the output of the SMPS.
12 more elements
Dependencies are inferred from the claim text.